Background: There are few studies in Spain which analyze the influence of individual, motivational and contextual variables, which might be different between underachieving, normally achieving and overachieving students. Method: A total of 1,398 Spanish high school students participated. Mixed-effects models were used to analyze data. Results: The results showed some evidence of: (a) Partial mediational effect of self-concept on the association between cognitive ability and academic achievement. (b) Higher levels of learning goals in the overachieving group than in the underachieving group, but no differences in achievement and reinforcement goals between groups. (c) Positive effect of learning strategies on attainment, both in the underachieving and the non-underachieving students. (d) Little effect of context variables on academic achievement, both in the underachieving and non-underachieving students. Conclusions: underachieving students seem to employ all the learning strategies considered to a lesser extent than normally and overachieving students. They also have a lower level of learning goals. On the contrary, overachieving students score more highly than under and normally achieving students in almost all of the above factors.